Volume governor for a flowing gaseous medium



1961 c. ALLANDER ETAL 2,997,061

VOLUME GOVERNOR FOR A FLOWING GASEOUS MEDIUM Filed April 25, 1958 2Sheets-Sheet 1 INVENTORSI CLAES A LLANDER 2 BIRGER LARKFELDT ATTYS' Aug.22, 1961 c. ALLANDER El'Al. 2,997,061

VOLUME GOVERNOR FOR A FLOWING GASEOUS MEDIUM Filed April 25, 1958 2Sheets-Sheet 2 FIEZ.

ATTYS.

United States Patent Filed Apr. 25, 1958, Ser. No. 731,044 Claimspriority, application Sweden Apr. 30, 1957 3 Claims. ('Cl. 137-517) Thepresent invention relates to a volume governor for a flowing gaseousmedium, preferably to be used in ventilating plants, said governor beingconstructed as a flow passage for the medium and having one of its twoopposite walls movable and arranged to be actuated by the staticpressure of the medium at the inlet of the governor.

It is the practice in ventilating plants to use an automaticallyfunctioning volume governor in order to secure uniform air supply todifferent spaces in the ventilating system. Because of the use of highvelocity systems with their relatively high working pressure andsimultaneously increased requirements for noise-elimination, theproblems regarding the noise occurring in regulators and air injectingmeans have been accentuated. The main object of the present invention isto'produce a regulator satisfying high requirements fornoise-elimination and simultaneously having good governing properties.The governor according to the invention may also be used as ashutting-off valve.

In earlier embodiments of governors the pressure reducing effect of thegovernor has without any exceptions been based on the principle ofvarying the throttling of a channel which is very short with respect toits flow area. In a regulator, functioning in accordance with saidprinciple, the available pressure energy will be converted into anincreased energy in the air in form of whirls, i.e. (hydrodynamicallyexpressed) the pressure energy is bound to the air in form of turbulentwhirl energy. Because such an energy conversion always causes aconsiderable quality of free sound energy, such regulators must alwaysbe used in combination with a separate sound deadening means inventilating plants for human habitations. As known, the conversion ofpressure energy into heat takes place without the occurrence of whirls.This is the case in laminar currents, where the dependence of theviscosity will guarantee the energy absorption.

The deciding factor for the degree of the occurrence of whirls in a flowpassage for a medium is the actual Reynolds number for the flow. Thisnumber is defined as the product of the flow velocity of the medium andthe hydraulic diameter of said flow passage divided by the kineticviscosity of the flowing medium. The hydraulic diameter of a duct isdetermined by dividing its perimeter into its cross-sectional area andmultiplying by four. In a long channel a shifting from laminar toturbulent flow occurs at a value of the Reynolds number of about 2000.

As the length of the flow passage decreases said value will decreasedepending upon disturbances in the inlet of said passage. When the flowis laminar hardly any noise will occur and thus the most silent pressurereduction can be obtained in this kind of flow. The rule may thus be soformulated that for a constant pressure reduction, the noise willincrease with increasing Reynolds number and thus a method to satisfythe demand of noise elimination is to work with small Reynolds numbers.In order to obtain the necessary throttling or pressure reduction thereis a need for a length of the passage increasing with decreasingReynolds number and thus the length of said flow passage in accordancewith the invention should considerably increase the hydraulic diameterof same.

The present invention is based on this very fact and the governoraccording to the invention is thus constructed with a small hydraulicdiameter and further made with such a large length of the flow passageso that there is time enough for a laminar flow to arise. In this way aflow substantially free from whirls will be obtained and as thenecessary absorption of the pressure energy takes place without anysubstantial occurrence of whirls, the arising noise in the ventilatingsystem will be of no intensity to speak about. As the hydraulic diameteris of decided importance and said diameter is to be made small, the flowpassage of the governor at the usual air quantities must be given arather elongated cross section area. It has proved effective todimension the volume governor to correspond to the width of theventilating apparatus, in which the governor is to be used.

The volume governor according to the invention is mainly characterizedin that the flow passage is formed in such a manner that in any positionof the movable wall, the length of the flow passage as reckoned in theflow direction of the medium is considerably larger than its hydraulicdiameter, and its flow area is so dimena sioned that the medium flowsthrough the channel without the occurrence of any whirls. The volumegovernor is preferably so constructed that the length of the flowpassage exceeds five times the hydraulic diameter. The flow passageshould further suitably be given such a hydraulic diameter that theReynolds number does not exceed 2000 at the maximum flow velocity of thegaseous medium. For the purpose of eliminating as much as possible theoccurrence of disturbing noise, the Walls of the flow passage arecovered with a sound deadening material. In order to eliminate the needfor a separate valve for the gaseous medium the movable Wall may bearranged to entirely shut off the flow passage area for the gaseousmedium by a manual adjustment.

The invention will now be described more in detail with reference to theaccompanying drawings, wherein:

FIG. 1 shows a longitudinal cross section through an exemplifyingembodiment of a volume governor according to the invention.

FIG. 2 shows a cross section through a volume governor along the line2--2 in FIG. 1.

In the embodiment illustrated in the drawing a volume governor 1isconnected to a duct 2 for a gaseous medium, in which duct an opening2a is arranged for the application of the invented volume governor. Thecasing 3 of the governor 1 encloses a space 4 directly communioatingwith said duct, said space terminating into an outlet chamber 5 ofsmaller width. The walls of the casing are covered with asound-deadening material 3a, and adjacent said chamber 5 are formed tofunction as a seat for a valve means 6 movably arranged in said casing.The flow passage formed between said valve means and the walls of thecasing is designated 7. The valve means 6 is shaped as an elongatedplate having an inverted generally U-shaped cross-section, and has acovering 6a of sound-deadening material. The valve element 6 is guidedat both ends by an axially movable rod 8, mounted in two bushings 9 and10. A bushing 11 is fastened to said valve means and slidably engagessaid rod 8. The valve means 6 is actuated by the static pressureprevailing in the space 4 to move against said seat, and is counteractedby a helical spring 12 surrounding said rod 8. The spring 12, one end ofwhich rests against the valve means, supports at its opopsite end awasher 15, which, in turn, rests on a stop washer 13, fixed to the rod8. A membrane 17 is arranged between the washers 13 and 15 and isfastened to supporting plates 16 fixed to the end walls of said outletchamber 5.

in order to adjust the valve means 6 in different working positionsandif needed-entirely shut off the flow passages of the volume governor,the rod 8 is arranged to be axially movable. This movement is effectedby means of a lever 20, arranged on a shaft 21, said shaft beingarranged to be turned by means of an adjusting maneuvering knob or arm(not shown in the drawing). The free end of the lever 20 is equippedwith a stud 22, engaging a groove in a sleeve 19 fixed to the rod 8.TIllemovements of the rod 8 are transmitted .to the valve means by awasher 14 fixed to the rod 8. Between said washer 14 and the bushing 11there is'arranged a damping packing 18.

What we claim is:

1. A volume governor for a flowing gaseous medium, comprising achannel-like open-ended casing, a valve seat in said casing, an axiallydisplace-able valve disk cooperating with said seat, guiding means forsaid valve disk and biasing means tending to hold said valve disk at anormal position a predetermined distance from said valve seat againstthe pressure of the flowing gaseous medium and operable upon increase ofpressure of the medium to afford displacement of said valve disk towardsaid seat and to maintain said flow substantially constant,characterized in that the casing is formed'with a rectangular, veryelongated cross section area and with the valve seat constituted by aninwardly projecting part of each of two opposite longitudinal walls ofthe casing, the longitudinal edges of said valve disk conforming withsaid inwardly projecting parts of said side walls to form two narrowflow passages of uniform Width dimensioned so that the length of saidflow passages in the flow direction exceeds five times the hydraulicdiameter of same insaid normal position of the valve disk.

2. A volume governor according to claim '1 including a sound-deadeningmaterial covering the walls of the fiow passages.

3. A volume governor according to claim 1 characterized in that thebiasing means comprises springs attached to the guidingmeans for thevalve disk, said guiding means being axially displaceable rods at eachend of the valve disk and arranged to be manually adjustable to set thevolume governor for different, predetermined values of the medium flowand to entirely shut off the how passage area for the gaseous medium.

References Cited in the file of this patent UNITED STATES PATENTS569,943 Shirley Oct. 20, 1896 2,311,381 Green Feb. 16, 1943 2,644,389Dauphinee July 7, 1953 2,813,474 Kurth Nov. 19, 1957 FOREIGN PATENTS59,725 Germany Nov. 11,1891

